While the data showed that overall median PFS for Pfizer's drug did indeed exceed that for Nexavar, the difference was not statistically significant, the firm noted.

Mace Rothenberg, senior vice president of clinical development and medical affairs for Pfizer's Oncology Business Unit, said the findings are now being analysed “to determine whether further evaluation of Inlyta in specific subpopulations of treatment-naïve patients with advanced RCC would be warranted.”

A fuller set of data is to be presented at an upcoming medical congress, Pfizer said.

Inlyta is already on the market as a second-line treatment for advanced kidney cancer, having won regulatory approvals in the US, EU, Japan, Switzerland, Canada, Korea, and Australia, but does not hold a license for use as a first-line therapy.

Approval was based, in part, on the Phase III AXIS trial, in which Inlyta significantly extended PFS compared to Nexavar, with a median result of 6.7 months versus 4.7 months, respectively.